This study is an open-label extension of RFSP-AMDX-2010 study for those subjects who received treatment with amdoxovir (300 mg or 500 mg twice daily) for 12 weeks and benefited from it. This study will examine the safety and efficacy of the investigational HIV drug, amdoxovir (300 mg and 500 mg bid doses; N = up to 30) in combination with zidovudine and lopinavir/ritonavir for 36 weeks.